Twigg called for state schools to follow the lead of the private sector and offer pupils more after-school activities, such as sport and debating clubs.

Youngsters need to be taught to be team players, and build up their confidence, he said.

Twigg was expected to make the call publicly in a speech to the North of England Education Conference (NEEC) in Sheffield but was unable to attend at the last minute.

In a speech prepared for the conference, Twigg was due to say: "I believe we need to encourage state schools to offer more after-school activities.

"I have talked about the importance of our armed services becoming more involved in schools, with more cadet forces in state schools and a role for ex-service personnel to act as mentors for young people."

Twigg said that on a recent visit to a school, one 14-year-old girl told him that an armed services mentor had "changed her life - giving her a sense of self-discipline and rigour, helping get her back on the right track".

There are around 257 Combined Cadet Forces (CCF) in UK state and private schools, according to official figures.

It is thought the vast majority are in independent schools.

CCFs can be made up of a number of different services, including the Royal Navy, the Royal Air Force and the Army. Some also include the Royal Marines.

Competitive sport is also "critical", Twigg's speech said, so that pupils "can learn to be team players, to build confidence - learning to be able to win and lose".

"However, we are seeing a decline in the number of pupils doing two hours of sport and PE per week, and we have seen a reduction in the regulations and standards which protect playing fields."

Twigg accused the Government of "undermining the Olympic legacy" and insisted that Labour would give Ofsted powers to inspect sport in schools.

He suggested that schools needed to make sure their pupils were "life-ready" by the time they finished their studies.

"Developing character and resilience must be one of the aims of a modern curriculum," his speech stated.

"It means having an exam system that assesses the skills necessary to thrive in the modern economy."

Twigg's comments come weeks after ministers announced plans to send former soldiers into classrooms to instil discipline and raise results among troubled youngsters.

Under the plans, ex-servicemen and women would be recruited to teach teamwork, discipline and leadership skills through mentoring, outdoor activities and other group exercises such as military-style obstacle courses.

Four projects will be established to pass on military values to youngsters who have been excluded from school, the Government said.